How to increment a key in the dictionary?

I’m new to javascript and I’m trying to increment a key in the dictionary

var dic = {}
for (let i = 0; i < 100; i++) {
    dic['key']++        
}
console.log(dic)

I don’t get the incremented number, where am I going wrong?

Answer

You are trying to increment undefined since there is no key property in dic, thus you get NaN.

Instead, give the key property a default value:

var dic = {key: 0}
for (let i = 0; i < 100; i++) {
    dic['key']++        
}
console.log(dic)